1. Field of the Invention
The present invention relates generally to data and voice communications. More particularly, the present invention relates to DSL modems.
2. Background Art
Over the last several years, DSL (Digital Subscriber Line) service has experienced ever-increasing demand from the subscriber community. In addition, the need to support higher-bandwidth solutions such as on-demand video services has driven the need for the DSL technology to even a higher level of demand.
By way of introduction, DSL technology is a copper loop transmission technology that converts existing copper telephone wire into a high-speed data highway with broadband speeds. xDSL is a generic name for the various versions of DSL technologies, such as ADSL (Asymmetric DSL), HDSL (High bit-rate DSL), RADSL (Rate Adaptive DSL), etc. DSL technology achieves broadband speeds over the ordinary phone wire. Although traditional analog telephone conversations, faxes and modem transmissions are limited to a 3,400 hz analog voice channel with a maximum possible modem speed of 56 kbps, DSL transmits a broader range of frequencies over existing copper telephone wire to achieve speeds over 30 times faster than a 56k modem. This significant increase in speed is possible because DSL uses a dedicated secure copper wire circuit that does not go through analog telephone switching equipment and because digital data (not an analog signal) is being transmitted.
Traditional phone service, namely “Plain Old Telephone Service” or “POTS” connects a home or small business to a telephone company office over copper wires that are wound around each other and called twisted pair. Regular voice signals travel over phone lines at frequencies ranging from 0 kHz to 4 kHz. Standard modems or analog modems use the same range of frequencies as voice, and communicate data in analog form over phone lines.
In contrast, DSL uses frequencies between 25 kHz and 1 MHz. DSL is a technology that assumes digital data does not require change into analog form and back. Digital data is transmitted to a host computer directly as digital data and this allows the phone company to use a much wider bandwidth for transmitting data to the host computer. Meanwhile, the telephone signal can be separated into voice band frequencies of 0-4 kHz and DSL bands frequencies of higher than 4 kHz using a filter that is typically referred to as a splitter, so that the voice band may still be used to transmit an analog signal concurrently with using DSL bands.
FIG. 1 illustrates conventional DSL system 100 for installation at homes or offices. As shown, DSL system 100 includes splitter 105 that receives telephone line signal 102. Splitter 105 is a filter that splits telephone line signal 102 into voice band signal 107 that carries frequencies of 0-4 kHz and DSL bands signal 109 that carries DSL bands frequencies of higher than 4 kHz. As further shown in FIG. 1, voice band signal 107 is communicated between splitter 105 and telephone 115, and DSL bands signal 109 is communicated between splitter 105 and DSL modem 110.
A great drawback of conventional DSL system 100 is that it fails to integrate analog voice and DSL communications, so that it can support analog voice and DSL communications in a single device. Rather, conventional DSL system 100 requires the user to use telephone 115 in addition to computer 120 for answering incoming calls via voice band 107.
A solution that present systems offer for having a fully integrated telephone usage from computer 120 is to include a VoIP (Voice over Internet Protocol) phone system in computer 120. In other words, in addition to data, voice communication is also supported through DSL bands 109. However, such solution requires expensive infrastructures, such as routers, cabling, VoIP phone equipment, VoIP-enabled APBX, etc., which are not economical for home and small office applications that already have conventional telephone equipment that utilize regular phone lines.
Accordingly, there is a need to overcome the drawbacks and deficiencies in the art by providing methods and systems that can offer more affordable and less complicated alternatives to conventional solutions for integrating analog voice communications and DSL modems.